here is what i do:
1. install whatsapp on my S3
2. Go to your old phone.  Search for the whatsapp folder.  In there, there is a folder called databases.  there should be a (few) file with extension .crypt.
3. copy all the .crypt file from the old phone to the same folder in S3.
4. Uninstall whatsapp on S3
5. install whatsapp on S3 again.

when u install again, verify yur phone number.  after tat whatsapp will recognise u hv backup and asked if you want to restore.

works for me.

officially yes, unofficially, the .apk have been extract and already widespread

it be more cool if you put your facebook, twiiter, instagram there, show it to your friend, its super cool, flipping through people status like a book